A liquid crystal display device has some advantages such as thin, light weight, low power consumption, or the like, compared to a display device using a cathode-ray tube. Further, since a liquid crystal display device can be widely applied to from the small-sized display device having a few inches of diagonal of a display portion to the large-sized display device having more than 100 inches, the liquid crystal display device is widely used as a display device of various electronic devices such as a mobile phone, a still camera, a video camera, a television receiver, and the like.
While the liquid crystal display device has excellent general versatility, there is a problem in that image quality is low compared to other display devices such as CRT and the like. The causes include: decrease of image quality when it is watched from an oblique angle due to large viewing angle dependence of display; low contrast because of leakage of the light from the backlight; low quality of moving image because of slow response speed, or the like.
However, image quality has been improved by development of a new liquid crystal mode in recent years. Instead of twisted nematic (TN) mode which has been conventionally used, the following various liquid crystal modes are developed and are put into practical use: an in-plane-switching (IPS) mode and an fringe field switching (FFS) mode which has excellent viewing angle characteristics, a vertical alignment (VA) mode which have high contrast ratio, an optical compensated birefringence (OCB) mode of which response speed is fast and quality of moving display is high, and the like.
Here, while the VA mode liquid crystal display device is easy to increase contrast ratio, there has been a problem that viewing angle dependence of display is still large. Therefore, multi-domain VA (MVA) mode and patterned VA (PVA) mode are developed by which a pixel is divided into a plurality of domains, and orientation of liquid crystal is changed in each domain so that wider viewing angle is realized. However, even if such a multi-domain method is used, enough viewing angle characteristics are not obtained.
Thus, patent document 1 (Japanese Published Patent Application No. 2003-295160) proposes to divide a pixel into a plurality of sub-pixels, and different signal voltages are applied to each sub-pixel, so that viewing angle dependence of display is averaged to increase viewing angle.